The impact of presidential appointments to the US Supreme Court: Cohesive and divisive voting within presidential blocs

Previous research by Robert Dahl and others has argued that the predominant pattern of Supreme Court decisionmaking reflects the appointments Presiden ts make to the Court. But each President's impact on the Court's decisions may be limited if that President appoints multiple justices who fail to vot e cohesively. In this article we evaluate the relative impact of five Presi dents' appointments by focusing on the group behavior of blocs of president ial appointees, emphasizing the extent to which such blocs vote cohesively or fragment in determining actual case outcomes. After first constructing " cohesion scores" for these "presidential blocs" to test the level of cohesi ve voting within each bloc, we examine particular configurations of votes i n order to evaluate each bloc's adherence to its appointing President's ide ological expectations on various issues. We find that in order for the chie f executive to wield the strong influence hypothesized by Dahl and others, three conditions must be met: (1) the President must have the opportunity t o appoint one or more justices; (2) when multiple justices are appointed, t hey must vote cohesively relative to the Court as a whole; and (3) voting c ohesion among multiple appointments must further the President's (and the p olitical majority's) policy preferences. Among modern Presidents, these con ditions were fulfilled only by the Nixon and Reagan appointments.